There have been many proposals for solid state electronic wristwatches and clocks which employ bistable electronic counters to display the time. Commonly, the indicating or display means are located on the top of a wristwatch since this is the location which is conventional for the dial face and hand pointers of a mechanical watch. For example, in U.S. Pat. Nos. 3,427,797, 3,540,209, 3,258,906, 3,466,498, 3,509,715, 3,276,200, 3,485,033 and 3,505,804, continuous reference is made to the watch face as a synonym for the top of the watch. U.S. Pat. No. 3,194,003 shows a similar form of electronic timepiece.
Various means have also been suggested for setting the time on an electronic clock, but these means have the disadvantage that they mimic the action of the mechanical watch by continuing the time readout during setting. This continuing readout is difficult to set at exact synchronization with an actual time signal. That is, since time is passing while the adjustment is taking place, the operator must watch his readout and at the same time observe another clock whose seconds indication is in motion or listen for a time signal and hope to advance his readout to within a few seconds of the actual time, after the signal. U.S. Pat. Nos. 3,456,152 and 3,195,011 relate to electronic timepieces having this form of time setting.
Such time setting means also carry from the lower order counters into the higher order counters. This is not objectionable when carrying from minutes to hours, however, it would be annoying to have the trial and error pulses feed into the days and months and years counters of a calendar watch. This would require further cycling to bring the counters back into proper place after adjusting the lower order counters for time zone changes or timing correction. While calendar circuitry has been previously considered, most suggestions leave the resetting of the day at the first of each month up to the operator. Months counters, and especially one with leap year provisions, have been deemed impractical due to the difficulties encountered in displaying and adjusting the counters. It has also been assumed that the calendar circuitry requires additional readouts and associated additional wiring interconnections.
In other proposals of electronic wristwatches, it has been assumed that a continuous display is required. When using light emitting elements, however, a continuous display requires a prohibitive power supply, in view of the efficiency of known light producing elements and the size of a battery required within the present state of the art. Furthermore, separate electronic components, such as resistors and capacitors for noise and signal control, have been found necessary in previous work. In addition, separate connections from each readout element to the elctronics circuit required as many as 33 connections for a four digit seven segment display and decimal points.